ADE7761
OPERATION
POWER SUPPLY MONITOR
Channel V2 (Voltage Channel)
The output of the line voltage transducer is connected to the
ADE7761 at this analog input. Channel V2 is a single-ended
voltage input. The maximum peak differential signal on
Channel 2 is 660 mV with respect to V2N. Figure 11 shows the
maximum signal levels that can be connected to Channel 2.
The ADE7761 contains an on-chip power supply monitor. The
power supply (VDD) is continuously monitored by the ADE7761.
If the supply is less than 4 V 5%, the ADE7761 goes into an
inactive state, that is, no energy is accumulated and the CF, F1,
and F2 outputs are disabled. This is useful to ensure correct
device operation at power-up and during power-down. The
power supply monitor has built-in hysteresis and filtering. This
gives a high degree of immunity to false triggering due to noisy
supplies.
V2
V
2P
+660mV + V
CM
V2
DIFFERENTIAL INPUT
±660mV MAX PEAK
V
V
2N
CM
V
COMMON MODE
±100mV MAX
CM
The power supply and decoupling for the part should be such
that the ripple at VDD does not exceed 5 V 5% as specified for
normal operation.
–660mV + V
CM
Figure 11. Maximum Signal Levels, Channel 2
V
DD
The differential voltage V2P–V2N must be referenced to a
common mode (usually AGND). The analog inputs of the
ADE7761 can be driven with common-mode voltages of up to
100 mV with respect to AGND. However, the best results are
achieved using a common mode equal to AGND.
5V
4V
0V
TIME
MISCAL Input
ADE7761
REVP - FAULT - CF -
F1 - F2 OUTPUTS
INACTIVE
ACTIVE
INACTIVE
The input for the power calibration in missing neutral mode is
connected to the ADE7761 at this analog input. MISCAL is a
single-ended voltage input. It is recommended to use a dc signal
derived from the voltage reference to drive this pin. The maxi-
mum peak differential signal on MISCAL is +660 mV with
respect to V2N. Figure 12 shows the maximum signal levels that
can be connected to the MISCAL pin.
Figure 9. On-Chip Power Supply Monitoring
ANALOG INPUTS
Channel V1 (Current Channel)
The voltage outputs from the current transducers are connected
to the ADE7761 here. Channel V1 has two voltage inputs, V1A
and V1B. These inputs are fully differential with respect to V1N.
However, at any one time, only one is selected to perform the
power calculation (see the Fault Detection section).
MISCAL
MISCAL
MISCAL
+660mV + V
CM
CM
DIFFERENTIAL INPUT
±660mV MAX PEAK
V
2N
V
COMMON MODE
±100mV MAX
V
CM
The maximum peak differential signal on V1A–V1N and V1B–V1N
is 660 mV.
AGND
Figure 10 shows the maximum signal levels on V1A, V1B, and V1N.
The differential voltage signal on the inputs must be referenced
to a common mode (usually AGND).
Figure 12. Maximum Signal Levels, MISCAL
The differential voltage MISCAL–V2N must be referenced to a
common mode (usually AGND). The analog inputs of the
ADE7761 can be driven with common-mode voltages of up to
100 mV with respect to AGND. However, best results are
achieved using a common mode equal to AGND.
V
1A
DIFFERENTIAL INPUT A
±660mV MAX PEAK
V
, V
1A 1B
V1
+660mV + V
CM
V
1N
COMMON MODE
±100mV MAX
V
CM
V
CM
Typical Connection Diagrams
V1
AGND
Figure 13 shows a typical connection diagram for Channel V1.
The analog inputs are being used to monitor both the phase
and neutral currents. Because of the large potential difference
between the phase and neutral, two current transformers (CTs)
must be used to provide the isolation. Note that both CTs are
referenced to analog ground (AGND); the common-mode
–660mV + V
DIFFERENTIAL INPUT B
±660mV MAX PEAK
CM
V
1B
Figure 10. Maximum Signal Levels, Channel 1
Rev. A | Page 13 of 28
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